Compared to bulk materials, a nanoparticle material worthy of notice now has electric, optic and/or magnetic properties, thus being subjected to numerous researches and investigations in a variety of applications. Owing to readily controllable chemical activities and large specific surface area, the nanoparticle material has been often used as a carrier for metal or semiconductor nanoparticles. Accordingly, a hybrid of nanoparticles and carbon nanotubes having synergistic effects thereof draws attention for a wide range of applications such as catalyst, sensor, hydrogen storage, nano-electronics, etc.
However, in spite of the foregoing advantages, it is difficult to homogeneously distribute nanoparticles with uniform particle size on carbon nanotubes without pretreatment of the carbon nanotubes. For instance, most of oxidation processes using strong acids may cause significant damage to a pure carbon nanotube wall while generating oxidation functional groups such as carboxylic acid. Covalent bond functionalization changes carbon-carbon bonds, more particularly, converts sp2-sp2 orbital into sp2-sp3 orbital. This may result in degradation in original and favorable properties of carbon nanotubes.
Carbon nitride nanotubes are carbon nanotubes substituted with nitrogen atoms. Nitrogen serves as a site for nucleation during adsorption of nanoparticles, which is advantageous in preparation of a hybrid. Accordingly, the aforementioned material has been proposed as an alternative solution to overcome the foregoing problems. For example, a research result for adsorption of silver nanoparticles on carbon nitride nanotubes was reported, wherein an adsorption of silver particles increases during reduction of metal salts without acid treatment for achieving functionalization. However, this method entailed a problem in that magnetic nanoparticles are liable to alteration of chemical stability since the nanoparticles are exposed to air or a solution.